Couplings have heretofore been known and used, wherein a smooth walled tube of plastic, rubber, or relatively soft metallic material, such as copper or aluminum, may be forced into a fitting assembly and retained therein against inadvertant removal, but they have been relatively complicated, comprising a great number of parts, and, expensive to manufacture and assemble. Furthermore, many of the prior art devices have had to be disassembled in order to remove the tube. In other instances it has been necessary to release the tube by the use of additional tools, or by manually manipulating moveable clamping jaws within the fitting.
Examples of prior art patents which have the foregoing disadvantages include the following:
______________________________________ Briegel 2,284,365 May 26, 1942 Ream 2,670,223 February 23, 1954 Sapy et al 3,653,689 April 4, 1972 Sands et al 3,844,585 October 29,1974 Legris 3,909,046 September 30,1975 Ellis 3,924,882 December 9, 1975 ______________________________________
Additional prior art patents relating to this general subject matter are:
______________________________________ Meier 3,637,240 January 25, 1972 Kay 3,817,561 June 18, 1974 Gallagher 3,858,913 January 7, 1975 Legris 3,889,989 June 17, 1975 Ellis 3,895,832 July 22, 1975 Legris 3,963,267 June 15, 1976 Belgian Pat. No. 541,480 October 15, 1955 ______________________________________